Method and apparatus for shape forming endovascular graft material

ABSTRACT

Methods and devices for molding a desired configuration into an endovascular graft section that is made of a plurality of layers of fusible material. Layers of fusible material are disposed on a shape forming mandrel with seams in the layers that may be configured to produce inflatable channels. The graft section and shape forming mandrel can be placed in a mold which constrains an outer layer or layers of fusible material while the inflatable channels are being expanded and the fusible material of the graft section fixed. In some embodiments, the fusible material of the graft section may be fixed by a sintering process.

RELATED APPLICATIONS

[0001] This application is related to U.S. patent application Ser. No.______ entitled “Endovascular Graft Joint and Method for Manufacture”,by Chobotov et al., and U.S. patent application Ser. No. ______ entitled“Advanced Endovascular Graft”, by Chobotov et al., and U.S. patentapplication Ser. No. ______ entitled “Method and Apparatus forManufacturing an Endovascular Graft Section”, by Chobotov et al. All ofthe above applications are commonly owned and were filed on even dateherewith. All of the above applications are hereby incorporated byreference, each in their entirety.

BACKGROUND

[0002] Embodiments of the device and method discussed herein relate to asystem and method for manufacturing intracorporeal devices used toreplace, strengthen, or bypass body channels or lumens of patients; inparticular, those channels or lumens that have been affected byconditions such as abdominal aortic aneurysms.

[0003] Existing methods of treating abdominal aortic aneurysms includeinvasive surgical methods with grafts used to replace the diseasedportion of the artery. Although improvements in surgical and anesthetictechniques have reduced perioperative and postoperative morbidity andmortality, significant risks associated with surgical repair (includingmyocardial infarction and other complications related to coronary arterydisease) still remain.

[0004] Due to the inherent hazards and complexities of such surgicalprocedures, various attempts have been made to develop alternativerepair methods that involve the endovascular deployment of grafts withinaortic aneurysms. One such method is the non-invasive technique ofpercutaneous delivery of grafts and stent-grafts by a catheter-basedsystem. Such a method is described by Lawrence, Jr. et al. in“Percutaneous Endovascular Graft: Experimental Evaluation”, Radiology(1987). Lawrence et al. describe therein the use of a Gianturco stent asdisclosed in U.S. Pat. No. 4,580,568 to Gianturco. The stent is used toposition a Dacron® fabric graft within the vessel. The Dacron® graft iscompressed within the catheter and then deployed within the vessel to betreated.

[0005] A similar procedure is described by Mirich et al. in“Percutaneously Placed Endovascular Grafts for Aortic Aneurysms:Feasibility Study,” Radiology (1989). Mirich et al. describe therein aself-expanding metallic structure covered by a nylon fabric, thestructure being anchored by barbs at the proximal and distal ends.

[0006] An improvement to percutaneously delivered grafts andstent-grafts results from the use of materials such as expandedpolytetrafluoroethylene (ePTFE) for a graft body. This material, andothers like it, have clinically beneficial properties. However,manufacturing a graft from ePTFE can be difficult and expensive. Forexample, it is difficult to bond ePTFE with conventional methods such asadhesives, etc. In addition, depending on the type of ePTFE, thematerial can exhibit anisotropic behavior. Grafts are generally deployedin arterial systems whose environments are dynamic and which subject thedevices to significant flexing and changing fluid pressure flow.Stresses are generated that are cyclic and potentially destructive tointerface points of grafts, particularly interface between soft andrelatively hard or high strength materials.

[0007] What has been needed is a method and device for manufacturingintracorporeal devices used to replace, strengthen or bypass bodychannels or lumens of a patient from ePTFE and similar materials whichis reliable, efficient and cost effective.

SUMMARY

[0008] An embodiment of the invention is directed to a mold formanufacture of an endovascular graft, or section thereof, which has atleast one inflatable channel or cuff. The mold has a plurality of moldbody portions configured to mate with at least one other-mold bodyportion to produce an assembled mold having a main cavity portion. Themain cavity portion has an inside surface contour that matches anoutside surface contour of the graft section with the at least oneinflatable channel or cuff in an expanded state. In some embodiments,the main cavity portion may include channel cavities, cuff cavities,longitudinal channel cavities or helical channel cavities which areconfigured to correspond to inflatable channels, inflatable cuffs,inflatable longitudinal channels or inflatable helical channels of thegraft when in an expanded state. In other embodiments, the mold can havea plurality of circumferential channel cavities and at least onelongitudinal channel cavity or helical channel cavity that transects thecircumferential channel cavities.

[0009] Another embodiment is directed to an outer constraint device inthe form of a mold for manufacture of an endovascular graft, or sectionthereof, which has at least one inflatable channel or cuff. The mold hasa first mold body portion having a main cavity portion with an insidesurface contour that is configured to correspond to an outside surfacecontour of the graft section with the at least one inflatable channel orcuff in an expanded state. The mold also has a second mold body portionconfigured to mate with the first mold body portion having a main cavityportion with an inside surface contour that is configured to correspondto an outside surface contour of the graft section with the at least oneinflatable channel or cuff in an expanded state.

[0010] A further embodiment of the invention is directed to a pressureline for use in the manufacture of an endovascular graft, or sectionthereof. The pressure line has an elongate conduit with an input end, anoutput end and a permeable section. The permeable section can have apermeability gradient which increases with distance from the input end.In one embodiment, the permeability of the pressure line increases about5 to about 20 percent per centimeter in a direction from the input endto the output end along the permeable section. The permeability gradientin the permeable section can be created by a plurality of outletorifices in the elongate conduit which increase in diameter with anincrease in distance from input end. In addition, such outlet orificescan be spaced longitudinally from each other so as to match alongitudinal spacing of a plurality of circumferential inflatablechannels of the endovascular graft.

[0011] Another embodiment of the invention includes a mandrel for shapeforming an endovascular graft, or section thereof. The mandrel has amiddle section and a first end section with at least a portion which hasa larger outer transverse dimension than an outer transverse dimensionof the middle section and which is removably secured to a first end ofthe middle section. A second end section is disposed at a second end ofthe middle section with at least a portion which has a larger outertransverse dimension than an outer transverse dimension of the middlesection. In a particular embodiment, the first end section and secondend section are removably secured to the middle section by threadedportions and a longitudinal axis of the first end section, second endsection and middle section can be substantially coaxial. In anotherembodiment, the middle section can have a pressure line recess in theform of a longitudinal channel in an outer surface of the middle sectionwhich is configured to accept a pressure line.

[0012] Embodiments of the invention can include an assembly formanufacture of an endovascular graft, or section thereof, which has atleast one inflatable cuff or channel on a section thereof. The assemblyconsists of a mandrel having an elongate body having an outer surfacecounter configured to support an inside surface of the graft section.The graft section having at least one inflatable cuff or channel isdisposed about at least a portion of the mandrel. A pressure line havingan elongate conduit with an input end, an output end and a permeabilitygradient which increases with distance from the input end is in fluidcommunication with an inflatable cuff or channel of the graft section. Amold is at least partially disposed about the graft section, thepressure line and the mandrel. The mold has a plurality of mold bodyportions configured to mate together to produce an assembled mold havinga main cavity portion. The main cavity portion has an inside surfacecontour that matches an outside surface contour of the graft sectionwith the at least one inflatable cuff or channel in an expanded state.The inside surface contour is configured to radially constrain an outerlayer or layers of the at least one inflatable cuff or channel duringexpansion of the cuff or channel. In some embodiments, the plurality oforifices of the elongate conduit of the pressure line can besubstantially aligned with circumferential channel cavities of the mold.

[0013] Embodiments of the invention which include methods for forming aninflatable channel or cuff of an endovascular graft, or section thereof,will now be described. An graft section is provided with at least oneinflatable channel or cuff formed between layers of graft material ofthe graft section in an unexpanded state. A mold is provided which has amain cavity portion With an inside surface contour that corresponds toan outside surface contour of the graft section with the at least oneinflatable channel or cuff in an expanded state. The graft section isthen positioned in the main cavity portion of the mold with the at leastone inflatable channel or cuff-of the graft section in an unexpandedstate positioned to expand into corresponding channel or cuff cavityportions of the main cavity portion. Once the graft section is properlypositioned within the main cavity portion of the mold, pressurized gasis injected into the at least one inflatable channel or cuff to expandthe at least one inflatable channel or cuff. Thereafter, the graftmaterial of the at least one inflatable channel or cuff is fixed withthe at least one inflatable channel or cuff in an expanded state.

[0014] In a particular embodiment of the method, a pressure line havingan elongate conduit with a permeable section which includes apermeability gradient can be placed in fluid communication with at leastone inflatable channel or cuff of the graft section. Thereafter,pressurized gas can be injected into the at least one inflatable channelor cuff through the permeable section of the pressure line. In addition,an optional internal radial support can be positioned within the graftsection prior to expansion of the at least one inflatable channel orcuff. The internal radial support may consist of a mandrel which isdisposed within the graft section prior to placing the graft sectioninto the mold so as to radially support the inside surface of the graftsection during injection of the pressurized gas. In one embodiment, thegraft material of the at least one inflatable channel or cuff is fixedby sintering. In another embodiment of a method for forming at least oneinflatable channel or cuff of an endovascular graft, or section thereof,a pressurized liquid can be injected into the inflatable channel or cuffof the graft section. Some expansion of the inflatable channel or cuffcan be carried out by vapor pressure from boiling of pressurized liquidduring fixing of the graft material with the liquid in the inflatablechannel or cuff.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 illustrates a layer of fusible material being positionedonto a shape forming mandrel.

[0016]FIG. 2 shows a first layer of fusible material disposed on a shapeforming mandrel.

[0017]FIG. 2A is a transverse cross sectional view of the first layer offusible material and the shape forming mandrel of FIG. 2 taken alonglines 2A-2A in FIG. 2.

[0018]FIG. 3 illustrates an additional layer of fusible material beingdeposited onto a shape forming mandrel.

[0019]FIG. 4 shows the first layer of fusible material being trimmed byan instrument.

[0020]FIG. 5 is a transverse cross sectional view of the layers offusible material and shape forming mandrel of FIG. 5 taken along lines5-5 of FIG. 4.

[0021]FIG. 6 illustrates additional layers of fusible material beingdeposited on the shape forming mandrel.

[0022]FIG. 7 illustrates an inflation line being positioned on the firstand additional layers of fusible material of FIG. 6.

[0023]FIGS. 7A and 7B illustrate the formation of the inflation line ofFIG. 7.

[0024]FIG. 8 shows two expandable members positioned on the layers offusible material of FIG. 7.

[0025]FIG. 9 illustrates the deposition of an adhesive or meltprocessible material adjacent a connector member of the graft bodysection under construction.

[0026]FIG. 10 shows another additional layer of fusible material beingdeposited onto the graft body section.

[0027]FIG. 11 illustrates excess fusible material being trimmed from thefirst end and second end of the graft body- section adjacent theconnector members.

[0028]FIG. 12 is an elevational view of the graft body section with thefusible material trimmed away and removed.

[0029]FIG. 13A is a side view from the right hand side of a five axisseam forming apparatus.

[0030]FIG. 13B is a side view from the left hand side of a five axisseam forming apparatus.

[0031]FIG. 13C is a front view of the five axis seam forming apparatusof FIGS. 13A and 13B.

[0032]FIG. 13D shows a stylus tip in contact with a transverse crosssectioned view of a cylindrical shape forming member with an axis of thestylus tip oriented at an angle with the tangent of the shape formingmember at the point of contact therebetween.

[0033]FIG. 13E illustrates a stylus tip in contact with a plurality oflayers of fusible material in a substantially flat configuration withthe longitudinal axis of the stylus tip at an angle with respect to aline which is orthogonal to the surface of the layers.

[0034]FIG. 13F is a front view of the seam forming apparatus with ashape forming mandrel and a graft body section on the shape formingmandrel positioned in the chuck of the seam forming member mount system.

[0035]FIG. 13G illustrates a distal extremity or tip of a stylus incontact with the layers of fusible material of the graft body section.

[0036]FIG. 13H illustrates the tip of a stylus in contact with layers offusible material of the graft body section, forming a seam in thelayers.

[0037]FIG. 14 shows inflation channels being formed in the layers offusible material on the shape forming mandrel by the seam formingapparatus stylus tip.

[0038]FIG. 15 shows the graft body section with the channel formationcomplete and pressurized fluid being injected into an inflatable channelnetwork in order to expand the inflatable channels.

[0039]FIG. 16A illustrates one half of an embodiment of a two-piece moldfor use during expansion of the inflatable channels formed by the seamforming apparatus. FIG. 16B is an end view showing the shape formingmandrel and graft body section within both halves of the mold.

[0040]FIG. 16C shows the graft body section and shape forming mandreldisposed within the mold cavity (with one half of the mold removed forclarity of illustration) with a fluid being injected into the inflatablechannels of the graft body section in order to keep the inflatablechannels in an expanded state during the fixing or sintering of thefusible material.

[0041]FIG. 17 illustrates an outer layer or layers of fusible materialbeing forced into the mold cavity of a portion of the mold bypressurized fluid as indicated by the dotted line.

[0042]FIG. 18 is an elevational view in partial section of an embodimentof an inflatable endovascular graft of the present invention.

[0043]FIG. 19 is an enlarged view of the graft of FIG. 18 taken at thedashed circle indicated by numeral 19 in FIG. 18.

[0044]FIG. 20 is an enlarged view in section- taken along lines 20-20 inFIG. 18.

[0045]FIG. 21 is a transverse cross sectional view of the graft of FIG.18 taken along lines 21-21 in FIG. 18.

[0046]FIG. 22 is a transverse cross sectional view of the graft of FIG.18 taken along lines 22-22 in FIG. 18.

[0047]FIG. 23 is a transverse cross sectional view of the graft of FIG.18 taken along lines 23-23 in FIG. 18.

[0048]FIG. 24 is an elevational view of an embodiment of a shape formingmandrel with a pressure line recess.

[0049]FIG. 25 is a transverse cross sectional view of the shape formingmandrel of FIG. 24 taken at lines 25-25.

[0050]FIG. 26 is a transverse cross sectional view of the shape formingmandrel of FIG. 24 taken at lines 26-26.

[0051]FIG. 27 shows an end view of a mold body portion. FIG. 28 shows aside view of a longitudinal section of a mold body portion.

[0052]FIG. 29 is a perspective view of a mold body portion separatedfrom another mold body portion.

[0053]FIG. 30 shows an elevational view of a pressure line havingfeatures of the invention.

[0054]FIG. 31 is a transverse cross sectional view of the pressure lineof FIG. 30 taken at lines 31-31.

[0055]FIG. 32 is a transverse cross sectional view of the pressure lineof FIG. 30 taken at lines 32-32, which shows a D-shaped configuration ofa portion of the pressure line.

[0056]FIG. 33 is a transverse cross sectional view of the pressure linewith exit ports of FIG. 30 taken at lines 33-33.

[0057]FIG. 34 shows a graft section and shape forming mandrel disposedwithin a mold cavity portion with one of the mold body portions notshown for clarity of illustration.

[0058]FIG. 35 is a transverse cross sectional view of the graft section,mandrel for shape forming the endovascular graft, and the pressure lineembedded within the layers of the fusible material taken at lines 35-35of FIG. 34.

[0059]FIG. 36 is an enlarged view showing the pressure line within thelayers of fusible material at encircled area 36 of FIG. 35.

[0060]FIG. 37 is a top partial cutaway view of the graft section landshape forming mandrel disposed within a mold cavity portion, with one ofthe mold body portions not shown for clarity of illustration, showingthe pressure line disposed within a longitudinal channel of the graftand a gas being injected into the pressure line of the graft section,expanding the inflatable channels and cuffs.

[0061]FIG. 38 is a top partial cutaway view of the graft section andshape forming mandrel disposed within a mold cavity portion, with one ofthe mold body portions not shown for clarity of illustration, showingthe pressure line disposed within a longitudinal channel and with theinflatable channels and cuffs in an expanded state.

[0062]FIG. 39 is a top partial cutaway view of an alternate embodimentof a graft section and shape forming mandrel disposed within a moldcavity portion, with one of the mold body portions not shown for clarityof illustration, showing the pressure line disposed within a temporaryexpansion channel that is in fluid communication with an expandedhelical inflatable channel.

[0063]FIG. 40 shows the graft section of FIG. 39 with the temporaryexpansion channel sealed.

[0064]FIG. 41 is a top partial cutaway view of an alternate embodimentof a graft section and shape forming mandrel disposed within a moldcavity portion, with one of the mold body portions not shown for clarityof illustration, with a pressure line disposed within a temporaryexpansion channel.

[0065]FIG. 42 shows the graft section of FIG. 41 with the temporaryexpansion channel sealed in selected portions.

DETAILED DESCRIPTION

[0066]FIG. 1 illustrates a sheet of fusible material 10 stored on anelongate drum 11. The drum 11 is rotatable, substantially circular intransverse cross section and has a transverse dimension in thelongitudinal center 12 that is greater than the transverse dimension ofeither end of the drum. The sheet of fusible material 10 is being rolledfrom the elongate drum in a single layer 13 onto an interior surfacesupport means in the form of a cylindrical or tapered (conical) shapeforming member or mandrel 14 to form a body section 15 of anendovascular graft 16. The body section 15 has a proximal end 17 and adistal end 18. For the purposes of this application, with reference toendovascular graft devices, the proximal end 17 describes the end of thegraft that will be oriented towards the oncoming flow of bodily fluid,usually blood, when the device is deployed within a conduit of apatient's body. The distal end 18 of the graft is the end opposite theproximal end.

[0067] A single layer of fusible material 13 is a term that generallyrefers to a sheet of material that is not easily separated by mechanicalmanipulation into additional layers. The shape forming mandrel 14 issubstantially cylindrical in configuration, although otherconfigurations are possible. Middle section 20 of mandrel 14 shown inFIGS. 1-2 has a transverse dimension which is smaller than thetransverse dimension of a first end section 21 and a second end section22. The shape forming mandrel may have a first tapered section 23 at thefirst end and a second tapered section 24 at the second end. The sheetof fusible material 10 is shown being rolled off the elongate drum 11 inthe direction indicated by the arrow 11A with the lead end 25 of thefirst layer of fusible material 10 oriented longitudinally along anoutside surface 14A of the shape forming mandrel 14.

[0068] The fusible material in the embodiment illustrated in FIG. 1 isePTFE that ranges from about 0.0005 to about 0.010 inch in thickness;specifically from about 0.001 to about 0.003 inch in thickness. Thesheet being disposed or rolled onto the shape forming mandrel 14 mayrange from about 2 to about 10 inches in width; specifically, from about3 to about 7 inches in width, depending on the indication and size ofthe end product.

[0069] The ePTFE material sheet 10 in FIG. 1 is a fluoropolymer with anode and fibril composition with the fibrils oriented in primarily auniaxial direction substantially aligned with the longitudinal axis ofshape forming mandrel 14. Other nodal/fibril orientations of ePTFE couldalso be used for this layer, including multiaxially oriented fibrilconfigurations or uniaxial material oriented substantiallycircumferentially about shape forming mandrel 14 or at any desired anglebetween substantial alignment with the longitudinal axis and substantialalignment with a circumferential line about the shape forming mandrel14. Uniaxially oriented ePTFE materials tend to have greater tensilestrength along the direction of fibril orientation, so fibrilorientation can be chosen to accommodate the greatest stresses imposedupon the finished product for the particular layer, combination oflayers, and portion of the product where such stress accommodation isneeded.

[0070] The layers of fusible material made of ePTFE are generallyapplied or wrapped in an unsintered state. By applying the ePTFE layersin an unsintered or partially sintered state, the graft body section 15,upon completion, can then be sintered or fixed as a whole in order toform a cohesive monolithic structure with all contacting surfaces ofePTFE layers achieving some level of interlayer adhesion. It may,however, be desirable to apply some layers of fusible material that havebeen pre-sintered or pre-fixed in order to achieve a desired result orto assist in the handling of the materials during the constructionprocess. For example, it may be desirable in some embodiments to sinterthe single layer 13 of fusible material applied to the shape formingmandrel 14 in order to act as a better insulator between the shapeforming mandrel 14, which can act as a significant heat sink, andsubsequent layers of fusible material which may be welded by seamformation in some locations in order to create inflatable channels.

[0071] The amount of expansion of the ePTFE material used for theconstruction of endovascular grafts and other devices can varysignificantly depending on the desired characteristics of the materialand the finished product. Typically, the ePTFE materials processed bythe devices and methods discussed herein may have a density ranging fromabout 0.4 to about 2 grams/cc; specifically, from about 0.5 to about 0.9grams/cc. The nodal spacing of the uniaxial ePTFE material may rangefrom about 0.5 to about 200 microns; specifically, from about 5 to about35 microns. The nodal spacing for multiaxial EPTFE material may rangefrom about 0.5 to about 20 microns; specifically, from about 1 to about2 microns.

[0072] Although FIG. 1 illustrates a layer of fusible material that ismade of ePTFE, the methods described herein are also suitable for avariety of other fusible materials. Examples of other suitable fusiblematerials for endovascular graft construction and other applicationsinclude PTFE, porous PTFE, ultra high molecular weight polyethylene,polyesters, and the like.

[0073]FIGS. 2 and 2A depict a first layer of fusible material 26disposed on the shape forming mandrel 14 with an overlapped portion 27of the first layer 26 on itself. A terminal end 28 of the first layer 26is seen extending longitudinally along the length of the shape formingmandrel 14. As the layer of fusible material is wrapped onto shapeforming mandrel 14, some tension may be provided on the sheet ofmaterial by the elongate drum 11. As a result of this tension and theflexible and conforming properties of the ePTFE material, the firstlayer of material 26 conforms closely to the outer contour of the shapeforming mandrel 14 as is illustrated in FIG. 2.

[0074] In some embodiments, it may be desirable to pass the tip of aseam forming tool or similar device (not shown) along the overlappedportion 27 of first layer 26 in a longitudinal direction in order toform a seam (not shown) along the overlapped portion 27 of first layer26. A tool suitable for forming such a longitudinal seam is a solderingiron with a smooth, rounded tip that will not catch or tear the layer offusible material. An appropriate operating temperature for the tip ofsuch a tool may range from about 320 to about 550 degrees Celsius;specifically, from about 380 to about 420 degrees Celsius.

[0075]FIG. 3 illustrates an additional layer of fusible material 30being disposed or wrapped onto the first layer of fusible material 26 ina manner similar to that described above for the first layer 26. Bothuniaxial and multiaxial ePTFE may be used for this additional layer 30.A lead end 31 of the additional layer can be seen adjacent the terminalend 28 of the first layer 26. Tension on the additional layer of fusiblematerial 30 helps to make the additional layer 30 conform to the shapeforming mandrel 14 as seen in the illustration. Although a singleadditional layer 30 is shown in FIG. 3 as being disposed onto the firstlayer 26, it is within the scope of the invention to wrap multipleadditional layers 30 of fusible material in this step. We have foundthat wrapping two additional layers 30 of multiaxial ePTFE onto thefirst layer 26 helps to form a useful graft body section 15.

[0076]FIG. 4 shows an optional step in which the first and additionallayers of fusible material 26 and 30 which form the graft body section15 under construction are trimmed by knife edge 32 or a similar toolwhich is pressed against the layers of material and movedcircumferentially about the shape forming mandrel 14. FIG. 5 is atransverse cross sectional view of the shape forming mandrel 14 andgraft body section 15 of FIG. 5 taken along lines 5-5 in FIG. 4. Theoverlapped portion 27 of the first layer 26 and an overlapped portion 33of the additional layer 30 of fusible material can be seen. It may bedesirable to create a longitudinal seam in the overlapped portion 33 ofthe additional layer 30 in a manner similar to that of the first layer26 discussed above using the same or similar tools.

[0077]FIG. 6 illustrates a proximal end wrap 34 of fusible materialbeing applied to the additional layer 30 of graft body section 15,preferably under some tension. We have found it useful to have end wrap34 be uniaxial ePTFE, with the fibrils of the end wrap material orientedcircumferentially about the shape forming mandrel 14, although otherorientations and types of ePTFE are possible. The end wrap material mayhave a thickness ranging from about 0.0005 to about 0.005 inch;specifically, from about 0.001 to about 0.002 inch. The width of the endwrap material may range from about 0.25 to about 2.0 inch; specifically,from about 0.5 to about 1.0 inch. One or more layers of end wrap 34 (inany desired orientation) may be built up onto the proximal end 17 ofgraft body section 15 on shape forming mandrel 14. The additional endwrap layer or layers 34 may be applied in a manner similar to that ofthe first layer 26 and additional layers 30 as discussed above.

[0078]FIG. 7 shows graft body section 15 with the end wrap layer 34completed with an inflation line 36 disposed on or near the distal end.18 of graft body section 15. The inflation line 36 may be constructed asshown in FIGS. 7A and 7B of ePTFE by wrapping one or more layers of thematerial about a cylindrical mandrel 37. A longitudinal seam 38 can thenbe formed in an overlapped portion of the layers by passing the tip of aseam forming tool 39 along the overlapped portion of the first layer ina longitudinal direction in order to form a seam 38 along the overlappedportion of the layers of the inflation line 36. A tool suitable forforming such a longitudinal seam is a soldering iron with a smoothrounded tip that will not catch or tear the layer of fusible material;operating temperatures for the tip may range as previously discussed.Alternatively, the inflation line 36 may be formed using an ePTFEextrusion placed over a mandrel.

[0079] Once seam 38 is formed in inflation line 36, the fusible materialof inflation line 36 may can be fixed or sintered by heating to apredetermined temperature for a predetermined time. For embodiments ofthe inflation line 36 made of ePTFE, the layers are sintered by bringingthe layered assembly to a temperature ranging from about 335 to about380 degrees Celsius (for unsintered material) and about 320 to about 380degrees Celsius (for sintering material that was previously sintered)and then cooling the assembly to a temperature ranging from about 180 toabout 220 degrees Celsius. The inflation line 36 may then be removedfrom mandrel 37 and disposed on a graft body assembly 40 as shown inFIG. 7. The inflation line 36 may be pre-fixed or pre-sintered to avoidhaving the inner surfaces of the inflation line 36 stick together duringthe construction and processing of the graft and possibly, block theinflation line 36.

[0080] In FIG. 8, expandable members in the form of a proximal connectormember 41 and a distal connector member 42 have been disposed onto thegraft body section 15 towards the respective graft body section proximalend 17 and distal end 18. The proximal connector member 41 is anelongate flexible metal element configured as a ring, with the ringhaving a zig-zag or serpentine pattern around the circumference of thering. The distal connector member 42 can have a similar configuration;note the feature of this element in which an extended apex 44 isdisposed over inflation line 36 to further stabilize graft section 15.This configuration allows the connector members 41 and 42 to be radiallyconstrained and radially expanded while maintaining a circular ringconfiguration. The embodiment of the connector members 41 and 42 shownin FIG. 8 may be constructed of any suitable biocompatible material;most suitable are metals, alloys, polymers and their composites known tohave superelastic properties that allow for high levels of strainwithout plastic deformation, such as nickel titanium (NiTi). Otheralloys such as stainless steel may also be used. Connector members 41and 42 shown are also configured to be self-expanding from a radiallyconstrained state. The serpentine pattern of the connector members 41and 42 is disposed over base layers of the graft body section as areconnector elements 43 which are disposed on certain apices 44 of theserpentine pattern of the connector members 41 and 42. The embodimentsof the connector members 41 and 42 shown in FIG. 8 have been shapeformed to lie substantially flat against the contour of the outersurface of the shape forming mandrel 14. Although the embodiment of FIG.8 illustrates connector members 41 and 42 being disposed upon the graftbody section 15, expandable members including stents or the like may beused in place of the connector members 41 and 42.

[0081] An optional adhesive or melt-processible material such as FEP orPFA may be deposited adjacent the connector members 41 and 42 prior tothe addition of additional layers of fusible material to the graft bodysection 15, as is shown in FIG. 9. Materials such as FEP or PFA can helpthe layers of fusible material to adhere to the connector members 41 and42, to inflation line 36 (in the case of distal member 42), and to eachother. In addition, such material may serve to provide strain reliefbetween connector members 41 and 42 and the adhered or bonded layers offusible material (and inflation line 36) adjacent the wire of theconnector members 41 and 42. It has been determined that one of theareas of greatest concentrated stress within an endovascular structuresuch as that described herein, when deployed within a dynamic biologicalsystem, such as an artery of a human patient, is at the junction betweenthe connector members 41 and 42 and graft body section 15. Therefore, itmay be desirable to include materials such as FEP or PFA or some otherform of strength enhancement or strain relief in the vicinity of thisjunction.

[0082] An outer overall wrap layer 50 may thereafter be applied to thegraft body section 15 and connector members 41 and 42 as shown in FIG.10. The outer overall wrap layer 50 can include one, two, three or morelayers of multiaxial ePTFE, usually about 2 to about 4 layers, butuniaxial ePTFE other suitable fusible materials, fibril orientation andlayer numbers could also be. used. The outer overall wrap layer 50 ismost usefully applied under some tension in order for the layer orlayers to best conform to the outer contour of the shape forming mandrel14 and graft body section 15. When the outer layer 50 comprisesmultiaxial ePTFE, there is generally no substantially preferredorientation of nodes and fibrils within the microstructure of thematerial. This result in a generally isotropic material whose mechanicalproperties, such as tensile strength, are generally comparable in alldirections (as opposed to significantly different properties indifferent directions for uniaxially expanded ePTFE). The density andthickness of the multiaxial material can be the same as or similar tothose dimensions discussed above.

[0083] Although not shown in the figures, we have found it useful to addone or more optional cuff-reinforcing layers prior to the addition of anoverall wrap layer 50 as discussed below in conjunction with FIG. 10.Typically this cuff-reinforcing layer is circumferentially applied tograft body section 15 at or near the graft body section proximal end 17so to provide additional strength to the graft body section proximal end17 in those designs in which a proximal cuff (and possibly a proximalrib) are used. Typically the graft experiences-larger strains duringfabrication and in service in the region of the proximal cuff,especially if a larger cuff is present. This optional cuff-reinforcinglayer typically is multiaxial ePTFE, although uniaxial ePTFE and othermaterials may be used as well. We have found effective acuff-reinforcing layer width from about 20 to about 100 mm;specifically, about 70 mm. Functionally, however, any width sufficientto reinforce the proximal end of graft body section 15 may be used.

[0084] Once the additional layer or layers of fusible material andadditional graft elements such as the connector members 41 and 42 andinflation line 36 have been applied, any excess fusible material may betrimmed away from the proximal end 17 and distal end 18 of graft bodysection 15. FIG. 11 illustrates one or more layers of fusible materialbeing trimmed from the proximal end 17 and distal end 18 of the graftbody section 15 so as to leave the connector members 41 and 42 embeddedbetween layers of fusible material but with the connector elements 43exposed and a distal end 51 of the inflation line 36 exposed as shown inFIG. 12. Once the fusible material has been trimmed from the proximalend 17 and the distal end 18, as discussed above, an additional processmay optionally be performed on the proximal end 17, distal end 18 orboth the proximal end and distal end 17 and 18. In this optional process(not shown in the figures), the outer wrap 50 is removed from a portionof the connector members 41 and 42 so as to expose a portion of theconnector members 41 and 42 and the additional layer of fusible material30 beneath the connector member 42 and the proximal end wrap 34 beneathconnector member 41. Once exposed, one or more layers of the additionallayer or layers 30 or proximal end wrap 34 may have cuts made therein toform flaps which can be folded back over the respective connectormembers 42 and 41 and secured to form a joint (not shown). One or morelayers of fusible material can then be disposed over such a joint toprovide additional strength and cover up the joint. The construction ofsuch a joint is discussed in copending U.S. patent application“Endovascular Graft Joint and Method for Manufacture” by Chobotov et al.which has been incorporated by reference herein.

[0085] Once the graft body section 15 has been trimmed, the entire shapeforming mandrel 14 and graft body section 15 assembly is moved to a seamforming apparatus 52 illustrated in FIGS. 13A-13H. This seam formingapparatus 52 has a base 53 and a vertical support platform 54 whichextends vertically upward from the back edge of the base 53. A mountsystem 55 is secured to the base 53 and for the embodiment shown in thefigures, consists of a motor drive chuck unit 56 secured to a riser 57and a live center unit 58 secured to a riser 59. Both risers 57 and 59are secured to the base 53 as shown. The axis of rotation 55A of thechuck 60 of the motor drive chuck unit 56 and the axis of rotation 55Bof the live center 61 of the live center unit 58 are aligned orconcentric as indicated by dashed line 55C. A motor is mechanicallycoupled to the chuck 60 of the motor drive chuck unit 56 and serves torotate the chuck 60 in a controllable manner.

[0086] A vertical translation rack 62 is secured to the vertical supportplatform 54 and extends from the base 53 to the top of the verticalsupport platform 54. A vertical car 63 is slidingly engaged on thevertical translation rack 62 and can be moved along the verticaltranslation rack 62, as shown by arrows 63A, in a controllable manner bya motor and pinion assembly (not shown) secured to the vertical car 63.A horizontal translation rack 64 is secured to the vertical car 63 andextends from the left side of the vertical car 63 to the right side ofthe vertical car 63. A horizontal car 65 is slidingly engaged on thehorizontal translation rack 64 and can be moved along the horizontalrack 64, as shown by arrow 64A, in a controllable manner by a motor andpinion assembly (not shown) which is secured to the horizontal car 65.

[0087] A stylus rotation unit 66 is slidingly engaged with a secondhorizontal translation rack 65A disposed on the horizontal car 65 andcan be moved towards and away from the vertical car 63 and verticalsupport platform 54 in a controllable manner as shown by arrow 66A. Astylus rotation shaft 67 extends vertically downward from the stylusrotation unit 66 and rotates about an axis as indicated by dashed line67B and arrow 67A in a controllable manner. A stylus mount 68 is securedto the bottom end of the rotation shaft 67 and has a main body portion69 and a stylus pivot shaft 70. A stylus housing 71 is rotatably securedto the stylus mount 68 by the stylus pivot shaft 70. A torsion spring 72is disposed between the proximal end of the stylus housing 73 and thestylus mount 68 and applies a predetermined amount of compressive, orspring-loaded force to the proximal end 73 of the stylus housing 71.This in turn determines the amount of tip pressure applied by a distalextremity 80 of a stylus tip 75 disposed at the distal end section 78 ofthe stylus 79 (which is in turn secured to the distal end section 76 ofthe stylus housing 71).

[0088] The base 53 of seam forming apparatus 52 is secured to a controlunit housing 77 which contains one or more power supplies, a CPU, and amemory storage unit that are used in an automated fashion to controlmovement between the graft body 15 section and the stylus tip 75 in thevarious degrees of freedom therebetween. The embodiment of the seamforming apparatus 52 described above has five axes of movement (ordegrees of freedom) between an object secured to the chuck 60 and livecenter, 61 and the stylus tip 75; however, it is possible to haveadditional axes of movement, such as six, seven, or more. Also, for someconfigurations and seam forming processes, it may be possible to usefewer axes of movement, such as two, three, or four. In addition, anynumber of configurations may be used to achieve the desired number ofdegrees of freedom between the stylus 79 and the mounted device. Forexample, additional axes of translation-or rotation could be added tothe mount system and taken away from the stylus rotation unit 66.Although the embodiment of the shape forming mandrel 14 shown in FIGS.1-17 is cylindrical, a five axis or six axis seam forming apparatus hasthe capability and versatility to accurately create seams of most anydesired configuration on a shape forming member or mandrel of a widevariety of shapes and sizes. For example, a “Y” shaped mandrel suitablefor generating a bifurcated graft body section could be navigated, bythe five axis seam forming apparatus illustrated herein, as well asother shapes. Finally, seam forming apparatus 52 illustrated herein isbut one of a number of devices and configurations capable of achievingthe seams of the present inventions.

[0089]FIG. 13D illustrates an enlarged view of a stylus tip 75 appliedto a rotating cylindrical surface 86B with the surface rotating in acounterclockwise direction as indicated by arrow 86A. The cylindricalsurface can support one or more layers of fusible material (not shown)between the distal extremity 80 of the stylus tip 75 and the surface 86Bwhich require seam to be formed therein. The stylus tip 75 has alongitudinal axis that forms an angle 86 with a tangent to the surfaceof the cylindrical surface indicated by dashed line 87. Although notnecessary, we have found it useful to have the object in contact withthe stylus tip 75 rotating or moving in a direction as show in FIG. 13D,relative to angle 86 in order to prevent chatter of the configuration ordistortion of fusible material on the surface 86A. In one embodiment,angle 86 may range from about 5 to about 60 degrees; specifically, fromabout 10 to about 20 degrees. It is also useful if the distal extremity80 of the stylus tip 75 has a smooth surface and is radiused. A suitableradius for one embodiment may range from about 0.01 to about 0.030 inch;specifically, from about 0.015 to about 0.02 inch.

[0090]FIG. 13E shows a similar relationship between a stylus tip 75 andhard surface 81. Surface 81 may have one or more layers of fusiblematerial (not shown) disposed thereon between distal extremity 80 andsurface 81. A longitudinal axis 75A of stylus tip 75 forms an angle 86with the dashed line 89 that is parallel to surface 81. Angle 88 in thisembodiment should range from about 5 to about 60 degrees; specifically,from about 10 to about 20 degrees, so to ensure smooth relative motionbetween surface 81 and tip 75. The surface 81 is shown moving relativeto the stylus tip 75 in the direction indicated by arrow 81A.

[0091] The pressure exerted by the extremity 80 of stylus tip 75 on thematerial being processed is another parameter that can affect thequality of a seam formed in layers of fusible material. In oneembodiment in which the stylus tip is heated, the pressure exerted bythe distal extremity 80 of the stylus tip 75 may range from about 100 toabout 6,000 pounds per square inch (psi); specifically, from about 300to about 3,000 psi. The speed of the heated stylus 75 relative to thematerial being processed, such as that of graft body section 15, mayrange from about 0.2 to about 10 mm per second, specifically, from about0.5 to about 1.5 mm per second. The temperature of the distal extremity80 of the heated stylus tip 75 in this embodiment may range from about320 to about 550 degrees Celsius; specifically, about 380 to about 420degrees Celsius.

[0092] Seam formation for ePTFE normally occurs by virtue of theapplication of both heat and pressure. The temperatures at the tip ofthe heated stylus 75 during such seam formation are generally above themelting point of highly crystalline ePTFE, which may range be from about327 to about 340 degrees Celsius, depending in part on whether thematerial is virgin material or has previously been sintered). In oneembodiment, the stylus tip temperature for ePTFE welding and seamformation is about 400 degrees Celsius. Pressing such a heated tip 75into the layers of ePTFE against a hard surface such as the outsidesurface of the shape forming mandrel) compacts and heats the adjacentlayers to form a seam with adhesion between at least two of, if not all,the layers. At the seam location and perhaps some distance away from theseam, the ePTFE generally transforms from an expanded state with a lowspecific gravity to a non-expanded state (i.e., PTFE) with a relativelyhigh specific gravity. Some meshing and entanglement of nodes andfibrils of adjacent layers of ePTFE may occur and add to the strength ofthe seam formed by thermal-compaction. The overall result of awell-formed seam between two or more layers of ePTFE is adhesion thatcan be nearly as strong or as strong as the material adjacent the seam.The microstructure of the layers may change in the seam vicinity suchthat the seam will be impervious to fluid penetration.

[0093] It is important to note that a large number of parametersdetermine the proper conditions for creating the fusible material seam,especially when that material is ePTFE. Such parameters include, but arenot limited to, the time the stylus tip 75 is in contact with thematerial (or for continuous seams, the rate of tip movement), thetemperature (of the tip extremity 80 as well as that of the material,the underlying surface 81, and the room), tip contact pressure, the heatcapacity of the material, the mandrel, and the other equipment, thecharacteristics of the material (e.g. the node and fibril spacing,etc.), the number of material layers present, the contact angle betweenthe tip extremity 80 and the material, the shape of the extremity 80,etc. Knowledge of these various parameters is useful in determining theoptimal combination of controllable parameters in forming the optimalseam. And although typically a combination of heat and pressure isuseful in forming an ePTFE seam, under proper conditions a useful seammay be formed by pressure at ambient temperature (followed by elevationto sintering temperature); likewise, a useful seam may also be formed byelevated temperature and little-to-no applied pressure.

[0094] For example, we have created seams in ePTFE that formed anintact, inflatable cuff by the use of a clamshell mold that presented aninterference fit on either side of a cuff zone for the ePTFE. Theapplication of pressure alone without using an elevated temperatureprior to sintering formed a seam sufficient to create a working cuff.

[0095]FIG. 13F depicts a front view of the seam forming apparatus 52with a shape forming mandrel 14 secured to the chuck 60 and the livecenter unit 58. The distal extremity of the heated stylus tip 75 is incontact with the graft body section 15 which is disposed on the shapeforming mandrel 14. The chuck 60 is turning the shape forming mandrel 14and graft body section 15 in the direction indicated by the arrow 60A toform a seam 81 between the layers of fusible material of the graft bodysection 15.

[0096]FIGS. 13G and 13H illustrate an enlarged view of the heated stylustip 75 in contact with the graft body section 15 in the process ofcreating one ore more seams 81 which are configured to form elongateinflatable channels 82 in the graft body section 15. The term“inflatable channels” may generally be described herein as asubstantially enclosed or enclosed volume between layers of fusiblematerial on a graft or graft section, and in some embodiments, in fluidcommunication with at least one inlet port for injection of inflationmaterial. The enclosed volume of an inflatable channel or cuff may bezero if the inflatable cuff or channel is collapsed in a non-expandedstate. The enclosed volume of an inflatable channel may or may not becollapsible during compression or compacting of the graft body section15.

[0097]FIG. 13H is an enlarged view in section of the distal extremity 80of the heated stylus tip 75 in contact with layers of fusible materialof graft body section 15. The layers of fusible material are beingheated and compressed to form a bond 15A therebetween. The seam formingapparatus can position the distal extremity 80 at any desired locationon the graft body section 15 by activation of one or more of the fivemotors controlled by the components in the control unit housing 77. Eachof the five motors controls relative movement between graft body section15 and distal extremity 80 in one degree of freedom. Thus, the distalextremity 80 may be positioned above the surface of the graft bodysection 15, as shown in FIG. 13C, and brought to an appropriatetemperature for seam formation, as discussed above, by resistive heatingor any other appropriate method. Once extremity 80 has reached thetarget temperature, it can be lowered by activation of the motor whichcontrols movement of the vertical car. The extremity 80 can be loweredand horizontally positioned by other control motors until it contactsthe graft body section in a desired predetermined position on graft bodysection 15, as shown in FIG. 13F.

[0098] Once distal extremity 80 makes contact with graft body section 15with the proper amount of pressure, it begins to form a seam between thelayers of the fusible material of the graft body section as shown inFIG. 13H. The pressure or force exerted by the extremity 80 on the graftbody section may be determined by the spring constant and amount ofdeflection of torsion spring 72 shown in FIGS. 13A and 13B; generally,we have found a force at the extremity 80 ranging from about 0.2 toabout 100 grams to be useful. As the seam formation process continues,the surface of graft body section 15 may be translated with respect tothe distal extremity 80 while desirably maintaining a fixed,predetermined amount of pressure between the distal extremity 80 and thelayers of fusible material of the graft body section. The CPU (or anequivalent device capable of controlling the components of apparatus 52)of the control unit housing 77 may be programmed, for instance, amathematical representation of the outer surface contour of any knownshape forming member or mandrel.

[0099] The CPU is thereby able to control movement of the five motors ofapparatus 52, so that distal extremity 80 may follow the contour of theshape forming member while desirably exerting a fixed predeterminedamount of pressure the layers of fusible material disposed between thedistal extremity 80 and the shape forming member. While seam formationis taking place, the pressure exerted by the distal extremity 80 on theshape forming member may be adjusted dynamically. The extremity 80 mayalso be lifted off the graft body section and shape forming member inlocations where there is a break in the desired seam pattern. Oncedistal extremity 80 is positioned above the location of the startingpoint of the next seam following the break, the extremity 80 may then belowered to contact the layers of fusible material, reinitiating the seamformation process.

[0100] Use of the seam forming apparatus 52 as described herein is butone of a number of ways to create the desired seams in the graft bodysection 15 of the present invention. Any suitable process and apparatusmay be used as necessary and the invention is not so limited. Forinstance, seams may also be formed in a graft body section 15 by the useof a fully or partially heated clamshell mold whose inner surfacescontain raised seam-forming extensions. These extensions may beconfigured and preferentially or generally heated so that when the moldhalves are closed over a graft body section 15 disposed on a mandrel,the extensions apply heat and pressure to the graft body sectiondirectly under the extensions, thereby “branding” a seam in the graftbody section in any pattern desired and in a single step, saving muchtime over the technique described above in conjunction with seam formingapparatus 52.

[0101] If the fusible material comprises ePTFE, it is also possible toinfuse or wick an adhesive (such as FEP or PFA) or other material intothe ePTFE layers such that the material flows into the fibril/nodestructure of the ePTFE and occupies the pores thereof. Curing or dryingthis adhesive material will mechanically lock the ePTFE layers togetherthrough a continuous or semi-continuous network of adhesive material nowpresent in and between the ePTFE layers, effectively bonding the layerstogether.

[0102]FIG. 14 illustrates a substantially completed set of seams 81formed in the layers of fusible material of the graft body section 15,which seams form inflatable channels 82. FIG. 15 illustrates graft bodysection 15 as fluid (such as compressed gas) is injected into theinflation line 36 and in turn into the inflatable channel network 84 ofbody section 15, as shown by arrow 84A. The fluid is injected topre-stress the inflatable channels 82 of body section 15 and expand themoutward radially. The fluid may be delivered or injected through anoptional elongate gas containment means having means for producing apermeability gradient in the form of a manifold or pressure line 85. Thepressure line 85 shown in FIG. 15 has a configuration with an input (notshown) located outside the inflation line and a plurality of outletapertures or orifices (not shown) that may be configured to provide aneven distribution of pressure within the inflatable channel network 84.Other fluid injection schemes and configurations are of course possible.

[0103] Because ePTFE is a porous or semi-permeable material, thepressure of exerted by injected fluids such as pressurized gas tends todrop off or diminish with increasing distance away from the outletapertures or orifices (not shown) of manifold or pressure line 85.Therefore, in some embodiments, pressure line 85 may comprise aperturesor orifices (not shown) which, when disposed in graft body section 15,progressively increases in size as one moves distally along the pressureline towards the proximal end 17 graft body section 15 in order tocompensate for a drop in pressure both within the inflatable channelnetwork 84 and within the manifold or pressure line 85 itself.

[0104] Once some or all of the inflatable channels 82 have beenpre-expanded or pre-stressed, the graft body section 15 and shapeforming mandrel assembly 89 may then be positioned within an outerconstraint means in the form of a mold to facilitate the inflatablechannel expansion and sintering process. One half of a mold 90 suitablefor forming an embodiment of a graft body section 15 such as that shownin FIG. 15 is illustrated in FIG. 16A. A mold half body portion 91 isone of two pieces of mold 90. A mold similar to mold 90 could be madefrom any number of mold body portions configured to fit together. Forexample, a mold 90 could be designed from three, four, five or more moldbody portions configured to fit together to form a suitable main cavityportion 93 for maintaining the shape of graft body section 15 duringchannel expansion and sintering. For certain configurations, a one piecemold may be used.

[0105] Mold body portion 91 has a contact surface 92 and a main cavityportion 93. Main cavity portion 93 has an inside surface contourconfigured to match an outside surface contour of the graft body sectionwith the inflatable channels in an expanded state. Optional exhaustchannels 92A may be formed in contact surface 92 and provide an escapeflow path for pressurized gas injected into the inflatable channelnetwork 84 during expansion of the inflatable channels 82.

[0106] The main cavity portion 93 of the FIGS. 16A-16B embodiment issubstantially in the shape of a half cylinder with circumferentialchannel cavities 94 for forming the various inflatable channels 82 ofgraft body section 15. Cavity 93 has a first tapered portion 95 at theproximal end 96 of mold 90. and a second tapered portion 97 at the molddistal end 98. FIG. 16B shows an end view of mold 90 with the two moldbody portions 91 and 100 pressed together with the assembly of the graftbody section 15 and shape forming mandrel 14 disposed mold cavity 93.

[0107]FIG. 16C shows the assembly of the graft body section 15 and shapeforming mandrel 14 disposed within mold 90, with the circumferentialinflatable channels 82 of the graft body section 15 aligned with thecircumferential channel cavities 94 of the main cavity portion 93. Onemold body portion 100 of mold 90 is not shown for the purpose of clarityof illustration. A pressurized fluid indicated as being delivered orinjected into manifold or pressure line 85 by arrow 85A.

[0108]FIG. 17 illustrates by the phantom lines how the outer layers 94Aof circumferential inflatable channel 82 of the fusible material of agraft body section 15 are expanded into the circumferential channelcavity 94 of mold cavity 93. The direction of the expansion of the outerlayers 94A to the position indicated by the phantom lines is indicatedby arrow 94B. A cross sectional view of the seams 83 of thecircumferential inflatable channel 82 is shown in FIG. 17 as well.

[0109] While the graft body section network of inflatable channels 84 isin an expanded state by virtue of pressurized material being deliveredor injected into pressure line 85, the entire assembly may be positionedwithin an oven or other heating device (not shown) in order to bring thefusible material of graft body section 15 to a suitable temperature foran appropriate amount of time in order to fix or sinter the fusiblematerial. In one embodiment, the fusible material is ePTFE and thesintering process is carried out by bringing the fusible material to atemperature of between about 335 and about 380 degrees Celsius;specifically, between about 350 and about 370 degrees Celsius. The moldmay then be cooled and optionally quenched until the temperature of themold drops to about 250 degrees Celsius. The mold may optionally furtherbe quenched (for handling reasons) with ambient temperature fluid suchas water. Thereafter, the two halves 91 and 100 of mold 90 can be pulledapart, and the graft assembly removed.

[0110] The use of mold 90 to facilitate the inflatable channel expansionand sintering process is unique in that the mold cavity portion 93 actsas a backstop to the graft body section so that during sintering, thepressure created by the injected fluid that tends to expand theinflatable channels outward is countered by the restricting pressureexerted by the physical barrier of the surfaces defining the mold cavity93. In general terms, therefore, it is the pressure differential acrossthe inflatable channel ePTFE layers that in part defines the degree ofexpansion of the channels during sintering. During the sintering step,the external pressure exerted by the mold cavity surface competes withthe fluid pressure internal to the inflatable channels (kept at a levelto counteract any leakage of fluid through the ePTFE pores at sinteringtemperatures) to provide an optimal pressure differential across theePTFE membrane(s) to limit and define the shape and size of theinflatable channels.

[0111] Based on this concept, we have found it possible to usealternatives to a mold in facilitating the inflatable channel expansionprocess. For instance, it is possible inject the channel network with aworking fluid that does not leak through the ePTFE pores and to thenexpand the network during sintering in a controlled manner, without anyexternal constraint. An ideal fluid would be one that could be usedwithin the desired ePTFE sintering temperature range to create thenecessary pressure differential across the inflatable channel membraneand the ambient air, vacuum, or partial vacuum environment so to controlthe degree of expansion of the channels. Ideal fluids are those thatpossess a high boiling point and lower vapor pressure and that do notreact with ePTFE, such as mercury or sodium potassium. In contrast, thenetwork of inflatable channels 84 can also be expanded during thefixation process or sintering process by use of vapor pressure from afluid disposed within the network of inflatable channels 84. Forexample, the network of inflatable channels 84 can be filled with wateror a similar fluid prior to positioning assembly in the oven, asdiscussed above. As the temperature of the graft body section 15 andnetwork of inflatable channels 84 begins to heat, the water within thenetwork of inflatable channels 84 begins to heat and eventually boil.The vapor pressure from the boiling water within the network ofinflatable channels 84 will expand the network of inflatable channels 84provided the vapor is blocked at the inflation line 85 or otherwiseprevented from escaping the network of inflatable channels.

[0112]FIG. 18 shows an elevational view in partial longitudinal sectionof an endovascular graft assembly 105 manufactured by the methods andwith the apparatus described above. Endovascular graft assembly 105comprises a graft body section 108 with a proximal end 106, a distal end107, and circumferentially oriented inflatable channels 111 shown in anexpanded state. A longitudinal inflatable channel 116 fluidlycommunicates with the circumferential inflatable channels 111.

[0113] An expandable member in the form of a proximal connector member112 is shown embedded between proximal end wrap layers 113 of fusiblematerial. An expandable member in the form of a distal connector member114 is likewise shown embedded between distal end wrap layers 115 offusible material. The proximal connector member 112 and distal connectormember 114 of this embodiment are configured to be secured or connectedto other expandable members which may include stents or the like, whichare not shown. In the embodiment of FIG. 18, such a connection may beaccomplished via connector elements 117 of the proximal and distalconnector members 112 and 114, which extend longitudinally outside ofthe proximal and distal end wrap layers 113 and 115 away from the graftbody section 108.

[0114] The FIG. 18 embodiment of the present invention features junction118 between the distal end wrap layers 115 of fusible material and thelayers of fusible material of a distal end 121 of the graft assemblymain body portion 122. There is likewise a junction 123 between theproximal end wrap layers 113 and the layers of fusible material of aproximal end 124 of the graft assembly main body portion 122. Thejunctions 118 and 123 may be tapered, with overlapping portions that arebound by sintering or thermomechanical compaction of the end wrap layers113. and 115 and layers of the main body portion 122. This junction 123is shown in more detail in FIG. 19.

[0115] In FIG. 19, six proximal end wrap fusible material layers 113 aredisposed between three fusible material inner layers 125 and threefusible material outer layers 126 of the main body portion proximal end124.

[0116]FIG. 20 illustrates a sectional view of a portion of the distalconnector member 114 disposed within the distal end wrap layers 115 offusible material. Connector member 114 is disposed between three outerlayers 127 of fusible material and three inner layers 128 of fusiblematerial. Optional seams 127A, formed by the methods discussed above,are disposed on either side of distal connector member 114 andmechanically capture the connector member 114. FIG. 21 likewise is atransverse cross sectional view of the proximal connector member 112embedded in the proximal end wrap layers 113 of fusible material.

[0117]FIG. 22 illustrates a transverse cross section of the longitudinalinflatable channel 116 formed between main body portion 122 outer layers131 and the main body portion 122 inner layers 132. FIG. 23 is atransverse cross section of graft main body portion 122 showing acircumferential inflatable channel 111 in fluid communication withlongitudinal inflatable channel 116. The circumferential inflatablechannel 111 is formed between the outer layers 131 of fusible materialof main body portion 122 and inner layers 132 of fusible material ofmain body portion 122.

[0118]FIG. 24 shows an alternate embodiment of an interior surfacesupport means in the form of an elongate mandrel 150 for shape formingan endovascular graft or section thereof. The mandrel 150 has an outersurface contour 151 configured to support an inside surface of an graftsection and is substantially cylindrical in configuration. The mandrel150 has a middle section 152 with a first end 153 and a second end 154.Additionally, a mandrel first end section 155 is disposed at first end153 of middle section and a mandrel second end section 156 is disposedat second end 154 of middle section 152. First and second end sections155 and 156 typically have an outer transverse dimension, at least aportion of which is larger than the outer transverse dimension of middlesection 152. First end section 155 is removably secured to the first end153 of middle section 152 by threaded portion 157. Alternatively, firstend section 155 may be removably secured by any other suitable mechanismor means such as attached by set screws, interlocking mechanisms or thelike. In some embodiments second end section 156 may be removablyattached, to second end 154 of the shape forming mandrel 150 by threadedportions 158 or alternate securement mechanisms. Middle section 152 ofmandrel 150 will typically range in length from about 50 to about 150mm, specifically from about 75 to about 100 mm, and typically has anouter transverse dimension from about 5 to about 50 mm; specificallyfrom about 15 to about 25 mm. Typically first and second end sections155 and 156 may have a tapered portion 161 and 162 adjacent first andsecond ends 153 and 154 of middle section 152, respectively. First endsection 155 is substantially cylindrical in configuration and typicallyhas an outer transverse dimension of about 15 to about 40 mm, such asabout 20 to about 30 mm. Second end section. 156 may have a similarconfiguration. Typically middle section 152, first end section 155 andsecond end section 156 are substantially circular or elliptical in shapeand cross section. They may be comprised of stainless steel but they mayalso be comprised of other metal alloys and materials such as aluminum,titanium, nickel-based alloys, ceramic materials, etc. In the embodimentof FIG. 24, middle section 152, first end section 155 and second endsection 156 are substantially coaxial over a longitudinal axis.

[0119] A pressure line recess 163 in the form of a longitudinal channelis formed in the outer surface 151 of the middle section 152 which isconfigured to accept a pressure line (not shown). The longitudinalchannel or pressure line recess 163 is typically semicircular orc-shaped in transverse cross section as shown in FIG. 25 and has aradius of curvature ranging from about 0.005 to about 0.090 inch. Thepressure line recess 163 extends along the middle section 152 of mandrel150 and terminates at first and second end sections 155 and 156.Alternate embodiments of the present invention include a pressure linerecess 163 that extends along the first or second end sections 155 and156.

[0120] Referring now to FIGS. 27-29, an outer constraint means in theform of a mold 165 for the manufacture of an endovascular graft, orsection thereof, is shown. The mold 165 is configured for themanufacture of a graft section which has at least one inflatable channelor inflatable cuff and can have the same or similar features as the mold90 shown in FIGS. 16A-16C and 17 above. A first mold body portion 166has a proximal end 167, a distal end 168 and is configured to mate witha second mold body portion 171 shown in FIG. 29. The first mold bodyportion 166 and second mold body portion 171 each has a main cavityportion 172 and 173, respectively, formed into the respective mold bodyportions 166 and 171. Main cavity portions 172 and 173 have insidesurface contours 174 and 175, respectively, that are configured tocorrespond to an outside surface contour of a graft section with theinflatable channels or cuffs in an expanded state. Circumferentialchannel cavities 176 are disposed on the inside surface contours 174 and175 of main cavity portions 172 and 173 and are configured to acceptcircumferential inflatable channels of an endovascular graft or graftsection. Circumferential inflatable cuff cavities 177 are disposed onthe inside surface contours 174 and 175 of the main cavity portions 172and 173 near or adjacent a first tapered portion 178 and second taperedportion 179 of the main cavity portions 172 and 173. First taperedportion 178 of main cavity portions 172 and 173 is disposed adjacent theproximal end 167 of mold 166. Second tapered portion 179 of main cavityportions 172 and 173 is disposed adjacent the distal end 168 of mold asshown in FIG. 28.

[0121] First mold body portion 166 has a contact surface 181 that isconfigured to mate with a contact surface 182 of the second mold bodyportion 171. The contact surface 182 of the second mold body portion 171in FIG. 29 has a plurality of exhaust channels 183 formed in the contactsurface 182 thereof; extending from main cavity portion 173 to aposition outside mold 165. Exhaust channels 183 allow pressurized gas orother material to escape from main cavity portion 172 and 173 of themold during inflation of the inflatable channels and cuffs. In theembodiment of FIG. 29, exhaust channels 183 are formed, or cut, incontact surface 182 of the second mold body portion 171 only and areconfigured to longitudinally align with the inflatable cuff cavities 177and inflatable channel cavities 176 of the main cavity portion 173 ofthe mold body portion 171, respectively. The longitudinal alignment ofexhaust channels 183 with the inflatable channel and cuff cavities 176and 177 provides for more efficient expansion of the inflatable channelsand cuffs. The exhaust channels 183 allow for a greater pressuredifferential between an inside volume of inflatable cuffs and channelsdisposed within the cavities 176 and 177 and a volume between an outsidesurface of the inflatable cuffs and channels and inside surface of themold 165 during inflation.

[0122] The mold 165 shown in FIGS. 27-29 includes two mold body portions166 and 171; however, other embodiments may include a plurality of moldbody portions with at least one of the mold body portions configured tomate with at least one of the other mold body portions to form anassembled mold having a main cavity portion. The main cavity has aninside surface contour that matches an outside surface contour of theendovascular graft, or section thereof, with at least one inflatablechannel or cuff of the graft section in an expanded state. Suchembodiments may have three, four, five or more mold body portionsconfigured to mate with each other as described above. In someconfigurations, even a single mold body portion can be used.

[0123] With the mold 165 assembled, main cavity portions 172 and 173typically extends along the length of each mold body portion 166 and 171and have a length of about 50 to 400 mm, specifically about 100 to about180 mm. The main cavity portions 172 and 173 typically have an innertransverse dimension of about 3 to 50 mm. Mold body portions 166 and 171may be comprised of a sintered metal material such as stainless steel orany other suitable material such as aluminum. Exhaust channels 183 maybe unnecessary in a mold embodiment made of sintered metal because theporous nature of sintered metal allows gas to escape from any portion ofthe closed sintered metal mold.

[0124] Another embodiment may include a mold body portion having a maincavity portion with at least one longitudinal channel cavity disposed onthe inside surface contour of a mold main cavity portion, and extendinglongitudinally along the inside surface contour. The longitudinalchannel cavity can have an inside surface contour that corresponds to anoutside surface contour of an inflatable longitudinal channel of anendovascular graft as shown in FIG. 34 in an expanded state. Anotherembodiment may have one or more mold body portions which have at leastone helical channel cavity disposed on the inside surface contour of themold main cavity portion. The helical channel cavity may have an insidesurface contour that corresponds to an outside surface contour of aninflatable helical channel of the endovascular graft in an expandedstate as shown in FIG. 39.

[0125] One of the difficulties encountered in expanding the graftsection inflatable channels and cuffs derives from the porosity of theflexible material that may be used for the graft body section, Forexample if a porous flexible material such as ePTFE is used for thegraft body section, the pressure of pressurized fluid such as a gasinjected from an inflation port will decrease with increasing distancefrom the inflation port as the gas escapes through the porous material.This can result in a graft section with inflatable channels and cuffswhich are inconsistently inflated and fixed. FIG. 30 depicts a pressureline 190 for use in the manufacture of an endovascular graft or sectionthereof which allows for a substantially even distribution of pressurewithin a network of inflatable channels and cuffs during inflation andfixing of the inflatable channels and cuffs.

[0126] The pressure line 190 shown is an elongate gas containment meansin the form of an elongate conduit 191 with a length of about 2 to about12 inches. The elongate conduit 191 has a proximal end 192, a distal end193, a proximal section 194 and a distal section 195. Note theconvention used herein where the distal end 193 of conduit 191 will bedisposed at the proximal end of graft body section.

[0127] A means for producing a permeability gradient in the form of apermeable section 196 is disposed along the conduit distal section 195.Typically disposed at the pressure line proximal end 192 is an adapteror fitting 197 such as a Luer adapter which has an, input port 198.Pressurized fluid (gas and/or liquid) may be injected into pressure line190 through input port 198. The permeable section 196 has a plurality oforifices 201 disposed therein which generally increase in diameter withan increase in distance from the proximal end 192, resulting in apermeability, gradient which increases in distance from the conduitproximal end 192. The distal end or extremity 193 of the pressure line190 can have a distal port (not shown) in addition to the plurality ofoutlet orifices 201 but may alternately be closed or partially closed.

[0128] Proximal section 194 of elongate conduit 191 is typicallycomprised of stainless steel but may alternately be comprised ofmaterials and metals such as aluminum, titanium, nickel-based alloys,ceramic materials, brass, etc. as well as polymeric tubing such aspolyimide. Proximal section 194 generally is cylindrical in transversecross section as shown in FIG. 31. The proximal section 194 has anangled step down portion 202 with first and second bends 203 and 204respectively, configured to mate with the mandrel tapered portion 161 or162 as shown in FIG. 24. Angled step down portion 202 can conform to atapered configuration of a graft or graft and mandrel assembly in whichthe pressure line 190 is placed on mandrel 150 during the formation ofan endovascular graft body section. Step down portion 202 may beD-shaped in transverse cross section, which allows a more streamlinedprofile for accommodation of the pressure line 190 within theendovascular graft or graft assembly. Step down portion 202 may form anangle of about 2 to about 30 degrees with respect to a longitudinal axis205 of a distal section of the elongate conduit 191.

[0129] Distal to step down portion 202, proximal section 194 is D-shapedin transverse cross section as shown in FIG. 32 and extends toward thedistal section 195. The flat portion 206 of the D-shaped cross sectionallows the pressure line 190 to have a lower profile when lying on asurface such as the outside surface of the tapered portion 161 or 162 ofa shape forming mandrel 150.

[0130] Distal section 195 has an elongate tubular configuration and issealingly secured to proximal section 194 at a junction 207. Distalsection 195 nominally has a circular transverse cross section and mayhave an outer transverse dimension of about 0.01 to about 0.1 inch;specifically, about 0.025 to about 0.035 inch. Distal section 195 isformed of a high durometer polymer such as polyimide or the like,although other suitable materials such as stainless steel may be used.The distal section 195 can be D-shaped along a proximal portion 208thereof when compressed within a distal portion 209 of the proximalsection 194 as shown in the transverse cross sectional view of FIG. 32.

[0131] The permeable section 196 has a proximal end 211 and a distal endand extends proximally from the distal end 193 of the pressure line 190for the embodiment shown in FIG. 30. The permeable section 196 has aplurality of outlet orifices 201 which increase in diameter toward thedistal end 193 of the pressure line 190. In one embodiment of thepressure line 190, the orifice or orifices 201 of the permeable section196 have increased area relative to the area of orifices disposedproximally thereof. In such an embodiment, the smallest and mostproximal orifices 213 may have a diameter of about 0.002 to about 0.007inch and the largest orifices 214 adjacent the distal end 212 of thepermeable section 196 may have a diameter of about 0.018 to about 0.022inch. The varied area of the orifices 201 provides for an increase inpermeability distally, which results in a predetermined permeabilitygradient that may be designed or adjusted to alleviate inconsistentexpansion of the inflatable channels and cuffs of a graft section. Thispermeability gradient may increase from about 5 to about 20 percent percentimeter along a direction from the proximal end 211 of permeablesection 196 to the distal end 212 of permeable section 196 in someembodiments.

[0132] Orifices 201 may be longitudinally spaced along the permeablesection 196 so that each opening or orifice 201 corresponds to a givenlongitudinal spacing and position of circumferential, helical, or othertypes of inflatable channels or cuffs of an endovascular graft or graftsection. Alignment of the orifices 201 with the inflatable channels orinflatable cuffs of a graft section can provide for a consistent andefficient inflation of the inflatable channels with fluid (liquid orgas) as it travels longitudinally along pressure line 190 and maintainsa constant pressure throughout as it fills the inflatable channels andcuffs. In addition, although the embodiment of pressure line 190 of FIG.30 is shown with a permeable section 196 formed by a plurality oforifices 201, other configurations may be used. For example, permeablesection 196 could be made from a porous material such as sintered metalor a porous polymer, wherein the porosity increases over a longitudinallength of the permeable section 196 in order to produce a desiredpermeability gradient over the length of permeable section 196.

[0133]FIG. 34 is a top view of an endovascular graft assembly 221disposed about an interior surface support means in the form of a shapeforming mandrel 222 and disposed within the main cavity portion 172 offirst mold body portion 166. The second mold body portion 171 of mold165 is not shown for the purpose of clarity of illustration. Theembodiment of the shape forming mandrel 222 may have the same or similarfeatures to the mandrel 150 shown in FIG. 24. The embodiment of theendovascular graft assembly 221 of FIG. 34 may have the same or similarfeatures to the endovascular graft assembly 105 of FIG. 18 discussedabove.

[0134] The endovascular graft assembly 221 has a graft body section 223having a proximal end 224, a distal end 225, and a plurality ofcircumferential inflatable channels 226 and inflatable cuffs 227 influid communication with a longitudinal inflatable channel or spine 228.An inflation port 231 is disposed at the distal end 225 of the graftbody section 223 and is in fluid communication with the longitudinalinflatable channel 228. Pressure line 190 is disposed within inflationport 231 and longitudinal inflatable channel 228, with the inflatablechannels 226 of the graft body section 223 in an unexpanded or collapsedstate. The pressure line 190 extends from the inflation port 231 to aproximal inflatable cuff 232.

[0135]FIG. 35 is a transverse cross sectional view of the graft bodysection 223, mandrel 222 and pressure line 190 and FIG. 36 is anenlarged view of the circled portion of FIG. 35.

[0136] Referring to FIG. 36, pressure line 190 is shown disposed withinthe longitudinal inflatable channel 228, which is disposed between outerlayers of flexible material 233 and inner layers of flexible material234 of graft body section 223. The inner layers of flexible material 234and outer layers of flexible material 233 are sealed together at a firstseam 235 and a second seam 236 which serve to form and definelongitudinal inflatable channel 228.

[0137]FIG. 37 is an enlarged view of the circled portion of FIG. 34 withthe graft body section 223 partially cut away for the purpose ofillustration. Pressure line 190 is positioned such that permeablesection 196 of pressure line 190 is disposed within the longitudinalinflatable channel 228 with the outlet orifices 201 aligned with and influid communication with the circumferential inflatable channels 226 andcircumferential inflatable cuffs 227 of graft body section 223.Additionally, circumferential inflatable channels 226 of the graft,pictured in a noninflated collapsed state, are substantially alignedwith and disposed adjacent corresponding circumferential channelcavities 176 of mold body portion 166.

[0138] Once pressure line 190 has been properly positioned within thelongitudinal inflatable channel 228 of graft body section 223,pressurized fluid, typically a gas, or other material may be injectedinto the network of inflatable channels and cuffs 237. The injection ofpressurized gas into the network of inflatable channels and cuffs 237forces flexible material 233 of the inflatable channels and cuffs 226and 227 to expand radially outward as indicated by the arrows 238 inFIG. 37. A more detailed illustration and description of this radialoutward expansion of the flexible material 233 may be found in FIG. 17and its corresponding discussion. The permeability gradient of thepermeable section 196 may be chosen so that the pressure and mass flowof pressurized gas exiting the outlet orifice 213 at the permeablesection proximal end 211 is substantially the same as the pressure andmass flow of pressurized gas exiting the outlet orifice 214 at thepermeable section distal end 212. This ensures that the inflatable cuff232 at the proximal end 224 of graft body section 223 will havesubstantially the same amount of inflation as the inflatable cuff 239 atthe distal end 225 of graft body section 223.

[0139] The pressure gradient may be configured such that the gaspressure at the circumferential inflatable channels 226 (disposedbetween the inflatable cuffs 227) will receive substantially the samepressure as well. It should be noted that in some embodiments of graftbody sections 223, inflatable cuffs 227 may have a larger volume thanadjacent inflatable channels 226. Therefore, inflatable cuffs 227 mayrequire more mass flow from a corresponding outlet orifice 201 than themass flow from an outlet orifice 201 corresponding to a circumferentialinflatable channel 226 in order to maintain the same pressure.

[0140] As the pressurized gas forces the flexible material 233 of thecircumferential inflatable channels 226 and inflatable cuffs 227radially outward, the radial outward movement of the material 233 isultimately checked by the inside surface contour 174 of thecircumferential channel cavities 176 and cuff cavities 177. Inwardradial movement or displacement of flexible material 233 is prevented byan outside surface 241 of mandrel 222. FIG. 38 shows the circumferentialinflatable channels 226 and inflatable cuffs 227 of graft body section223 in an expanded state. This allows the circumferential inflatablechannels 226 and inflatable cuffs 227 to be formed and then fixed byfixing the flexible material 233 and 234 of the inflatable channels andcuffs 226 and 227 while in an expanded state. As discussed above, if theflexible material is ePTFE, the flexible material may be fixed by asintering process.

[0141] For some non-bifurcated embodiments of graft body sections 223,pressurized gas may be injected at a rate of about 2 to about 15 scfh;specifically, about 5 to about 6 scfh. For such embodiment, the pressureof the pressurized gas can be from about 5 to about 30 psi. For somebifurcated embodiments of graft body sections 223, pressurized gas mayinjected at a rate of about 15 to about 30 scfh; specifically, about 18to about 20 scfh. For such bifurcated embodiments, the pressure of thepressurized gas can be from about 15 to about 60 psi. In anotherembodiment, the rate at which pressurized gas is injected into theinflatable channel and cuff network 237 of the graft body section 223may be normalized based on the surface area of that portion ofendovascular graft body section 223 that is being expanded. For somegraft body section 223 embodiments, there is no permanent longitudinalinflatable channel 228. For these embodiments, it may be desirable toinclude a temporary longitudinal inflation-channel in the graft bodysection in order to provide access to the inflatable channels of thegraft body section for injection of pressurized gas FIG. 39 shows agraft section 250 disposed within a mold body portion 251 having aproximal inflatable cuff 252, distal inflatable cuff 253, helicalinflatable channel 254 and temporary longitudinal inflatable channel255. The temporary longitudinal inflatable channel 255 is in fluidcommunication with proximal inflatable cuff 252, distal inflatable cuff253 and helical inflatable channel 254. A pressure line 256 is disposedwithin the temporary longitudinal inflatable channel 255 and has outletorifices 257 that are aligned with and correspond to the proximalinflatable cuff 252, distal inflatable cuff 253 and helical inflatablechannel 254. The inflatable channel 254 and cuffs 252 and 253 are shownin an expanded state. Outlet orifices 257 may be configured to produce apressure gradient that evenly distributes appropriate mass flow from thepressure line 256 to the inflatable cuffs 252 and 253 and inflatablehelical channel 254.

[0142] Once the flexible material of the inflatable channel and cuffs252, 253 and 254 is fixed while the inflatable channel and cuffs 254,252 and 253 are in the expanded state, pressure line 256 may be removedand the temporary longitudinal inflatable channel 255 sealed in desiredportions 258 so as to leave the inflatable cuffs 252 and 253 andinflatable helical channel 254 patent. Sealed portions 258 of thetemporary longitudinal inflatable channel 255 shown in FIG. 40 areformed by pressing the layers of flexible material 259 at the sealedportions locations flat together and forming an adhesion by adhesivebonding, thermomechanical sealing or any other suitable method. Asuitable material that may be used to seal the sealed portion of thetemporary longitudinal inflatable channel 255 is FEP; however, any othersuitable material such as silicone elastomer may be used. It may bedesirable to use an adhesion method for the sealed portions 258 thatmaintains a low profile and high degree of flexibility of the sealedportions of the temporary longitudinal inflatable channel 255.

[0143]FIG. 41 illustrates another embodiment of a graft body section 261having no permanent longitudinal inflatable channel. A temporarylongitudinal inflation channel 262 in the graft section 261 providesaccess to the circumferential inflatable channels 263 and thelongitudinal inflatable channel segments 264 of the graft section 261for injection of pressurized gas. FIG. 41 shows graft section 261disposed within a mold body portion 265 and having a proximal inflatablecuff 266, distal inflatable cuff 267, circumferential inflatablechannels 263, longitudinal inflatable channel segments 264 and temporarylongitudinal inflatable channel 262. Temporary longitudinal inflatablechannel 262 is in fluid communication with the other inflatable cuffsand channels 266, 267, and 263. A pressure line 268 is disposed withinthe temporary longitudinal inflatable channel 262 and has outletorifices 269 that are aligned with and correspond to the proximalinflatable cuff 266, distal inflatable cuff 267 and circumferentialinflatable channels 263. The inflatable channels 263 and cuffs 266 and267 are shown in an expanded state. Outlet orifices 269 may beconfigured to produce a pressure gradient that evenly distributespressure and appropriate mass flow from pressure line 268 to inflatablecuffs 266 and 267 and inflatable circumferential channels 263.

[0144] Once a flexible material 270 of the inflatable channels 263 andcuffs 266 and 267 are fixed while the inflatable channels 263 and cuffs266 and 267 are in the expanded state, pressure line 268 may be removed,and the temporary longitudinal inflatable channel 262 may be sealed indesired portions 271 so as to leave the inflatable cuffs 266 and 267 andinflatable channels 263 patent. Sealed portions 271 of temporarylongitudinal inflatable channel 262 shown in FIG. 42 may be formed in amanner similar to the sealed portions 258 of the temporary longitudinalinflatable channel 255 of FIG. 40.

[0145] While particular forms of embodiments of the invention have beenillustrated and described, it will be apparent that variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

We claim:
 1. A mold for the manufacture of an endovascular graft orsection thereof which has at least one inflatable channel or cuff,comprising: a plurality of mold body portions configured to mate with atleast one of the other mold body portions to produce an assembled moldhaving a main cavity portion with an inside surface contour that matchesan outside surface contour of the endovascular graft section with the atleast one inflatable channel or cuff in an expanded state.
 2. The moldof claim 1 further comprising at least one channel cavity that has aninside surface contour that corresponds to an outside surface contour ofthe at least one inflatable channel in an expanded state.
 3. The mold ofclaim 1 further comprising at least one cuff cavity that has an insidesurface contour that corresponds to an outside surface contour of the atleast one inflatable cuff in an expanded state.
 4. The mold of claim Ifurther comprising at least one longitudinal channel cavity that has aninside surface contour that corresponds to an outside surface contour ofan inflatable longitudinal channel of the graft section in an expandedstate.
 5. The mold of claim 1 further comprising at least one helicalchannel cavity that has an inside surface contour that corresponds to anoutside surface contour of an inflatable helical channel of the graftsection in an expanded state.
 6. The mold of claim 1 wherein the moldbody portions comprise sintered metal.
 7. The mold of claim 1 furthercomprising at least one exhaust channel in fluid communication with themain cavity portion of the mold and a position outside the mold.
 8. Themold of claim 7 wherein the exhaust channel is disposed on a contactsurface of a mold body portion.
 9. The mold of claim 1 wherein the moldbody portions comprise aluminum.
 10. The mold of claim 1 wherein themain cavity portion has a length of about 50 to about 300 mm.
 11. Themold of claim 1 wherein the main cavity portion has an inner transversedimension of about 4 to about 50 mm.
 12. The mold of claim 2 comprisinga plurality of channel cavities configured as circumferential channelcavities and at least one longitudinal channel cavity in fluidcommunication with the circumferential channel cavities.
 13. The mold ofclaim 2 comprising a plurality of channel cavities configured ascircumferential channel cavities and at least one helical channel cavityin fluid communication with the circumferential channel cavities. 14.The mold of claim 1 further comprising a first tapered portion disposedat a first end of the main cavity portion and a second tapered portiondisposed at a second end of the main cavity portion, wherein the firstand second tapered portions taper to an increased transverse dimensiontoward respective first and second ends of the mold.
 15. A mold formanufacture of an endovascular graft or section thereof which has atleast one inflatable channel or cuff, comprising: a first mold bodyportion having a main cavity portion with an inside surface contour thatis configured to correspond to an outside surface contour of the graftsection with the at least one inflatable channel or cuff in an expandedstate; and a second mold body portion configured to mate with the firstmold body portion having a main cavity portion with an inside surfacecontour that is configured to correspond to an outside surface contourof the graft section with the at least one inflatable channel or cuff inan expanded state.
 16. The mold of claim 15 further comprising at leastone channel cavity that has an inside surface contour that correspondsto an outside surface contour of the at least one inflatable channel inan expanded state.
 17. The mold of claim 15 further comprising at leastone cuff cavity that has an inside surface contour that corresponds toan outside surface contour of the at least one inflatable cuff in anexpanded state.
 18. The mold of claim 15 further comprising at least onelongitudinal channel cavity that extends longitudinally along an insidesurface contour of a main cavity portion of the mold and that has aninside surface contour that corresponds to an outside surface contour ofan inflatable longitudinal channel of the graft section in an expandedstate.
 19. The mold of claim 15 further comprising at least one helicalchannel cavity within the main cavity portion of the mold that has aninside surface contour that corresponds to an outside surface contour ofan inflatable helical channel of the graft section in an expanded state.20. The mold of claim 15 wherein the mold body portions comprise asintered metal.
 21. The mold of claim 15 further comprising at least oneexhaust channel in fluid communication with the main cavity portion anda position outside the mold.
 22. The mold of claim 15 wherein theexhaust channel is disposed on a contact surface of the mold bodyportion.
 23. The mold of claim 15 wherein the mold body portionscomprise aluminum.
 24. The mold of claim 15 wherein the main cavityportion has a length of about 50 to about 300 mm.
 25. The mold of claim15 wherein the main cavity portion has an inner transverse dimension ofabout 5 to about 50 mm.
 26. The mold of claim 16 comprising a pluralityof channel cavities configured as circumferential channel cavities andat least one longitudinal channel cavity in fluid communication with thecircumferential channel cavities.
 27. The mold of claim 16 comprising aplurality of channel cavities configured as circumferential channelcavities and at least one helical channel cavity in fluid communicationwith the circumferential channel cavities.
 28. The mold of claim 15further comprising a first tapered portion disposed at a first end ofthe main cavity portion and a second tapered portion disposed at asecond end of the main cavity portion.
 29. A pressure line for use inthe manufacture of an endovascular graft or section thereof, comprising:an elongate conduit having an input end, an output end and a permeablesection that has a permeability gradient which increases with distancefrom the input end.
 30. The pressure line of claim 29 wherein thepermeability of the pressure line increases about 5 to about 20 percentper centimeter in a direction from the input end to the output end alongthe permeable section.
 31. The pressure line of claim 29 wherein thepermeability gradient results from a plurality of outlet orificesdisposed in the elongate conduit which increase in diameter with anincrease in distance from the input end.
 32. The pressure line of claim31 wherein the outlet orifices are spaced longitudinally from each otherso as to match a longitudinal spacing of a plurality of circumferentialinflatable channels of the endovascular graft.
 33. The pressure line ofclaim 29 further comprising an input port, a proximal section and adistal section wherein the proximal section comprises stainless steeland the distal section comprises a polymer.
 34. The pressure line ofclaim 33 wherein the distal section has an outer transverse dimension ofabout 0.01 to about 0.1 inch.
 35. The pressure line of claim 29 whereinthe length of the pressure line is about 2 to about 12 inches.
 36. Thepressure line of claim 29 wherein a transverse cross section of at leasta portion of the proximal section is D-shaped.
 37. A mandrel for shapeforming an endovascular graft, or section thereof, comprising: a middlesection; a first end section with at least a portion that has a largerouter transverse dimension than an outer transverse dimension of themiddle section and which is removably secured to a first end of themiddle section; and a second end section disposed at a second end of themiddle section with at least a portion that has a larger outertransverse dimension than an outer transverse dimension of the middlesection.
 38. The mandrel of claim 37 wherein the second end section isremoveably secured to a second end of the middle section.
 39. Themandrel of claim 38 wherein the first end section and second end sectionare removably secured to the middle section by threaded portions. 40.The mandrel of claim 37 wherein the middle section is about 50 to about150 mm in length.
 41. The mandrel of claim 37 wherein the outertransverse dimension of the middle section is about 5 to about 50 mm.42. The mandrel of claim 37 wherein the outer transverse dimension ofthe middle section is about 15 to about 30 mm.
 43. The mandrel of claim37 wherein the outer transverse dimension of the first end section isabout 15 to about 40 mm.
 44. The mandrel of claim 37 wherein the middlesection further comprises a pressure line recess that includes alongitudinal groove formed in an outer surface of the middle section andwhich is configured to accept a pressure line.
 45. The mandrel of claim39 wherein the first end section, second end section and middle sectioncomprise stainless steel.
 46. The mandrel of claim 37 wherein the firstend section, second end section and middle section are substantiallycircular or elliptical in transverse cross section.
 47. The mandrel ofclaim 44 wherein the transverse cross section of the longitudinalchannel has a radius of curvature of about 0.005 to about 0.05 inch. 48.The mandrel of claim 46 wherein a longitudinal axis of the first endsection, second end section and middle section are substantiallycoaxial.
 49. An assembly for manufacture of an endovascular graft orsection thereof which has at least one inflatable cuff or channel on thegraft section, comprising: a) a mandrel comprising an elongate bodyhaving an outer surface contour configured to support an inside surfaceof the endovascular graft; b) the graft section having at least oneinflatable cuff or channel disposed about at least a portion of themandrel; c) a pressure line comprising an elongate conduit having aninput end, an output end and a permeability gradient which increaseswith distance from the input end and which is in fluid communicationwith an inflatable cuff or channel of a main body portion of theendovascular graft; d) a mold at least partially disposed about thegraft section, the pressure line and the mandrel, comprising a pluralityof mold body portions configured to mate together to produce anassembled mold having a main cavity portion with an inside surfacecontour that matches an outside surface contour of the graft sectionwith the at least one inflatable cuff or channel in an expanded stateand configured to radially constrain an outer layer or layers of the atleast one inflatable cuff or channel during expansion of the cuff orchannel.
 50. The assembly of claim 49 wherein the pressure line is atleast partially disposed within an inflatable cuff or channel of thegraft.
 51. The assembly of claim 50 wherein the permeability gradient ofthe pressure line results from a plurality of orifices disposed in theelongate conduit which increase in diameter as distance from the inputend of pressure line increases.
 52. The assembly of claim 51 wherein theplurality of orifices are substantially aligned with circumferentialchannel cavities of the mold.
 53. The assembly of claim 49 wherein themandrel comprises a middle section; a first end section with at least aportion that has a larger outer transverse dimension than an outertransverse dimension of the middle section and which is removablysecured to a first end of the middle section; and a second end sectiondisposed at a second end of the middle section with at least a portionthat has a larger outer transverse dimension than an outer transversedimension of the middle section.
 54. The assembly of claim 53 whereinthe mandrel further comprises a pressure line recess that includes alongitudinal groove formed in an outer surface of the mandrel.
 55. Theassembly of claim 51 wherein the orifices of the pressure line aresubstantially aligned with inflatable channels of the main body portion.56. A method of forming at least one inflatable channel or cuff of anendovascular graft or section thereof comprising: a) providing a graftsection with at least one inflatable channel or cuff formed betweenlayers of graft material of the graft section in an unexpanded state; b)providing a mold comprising a main cavity portion having an insidesurface contour that corresponds to an outside surface contour of thegraft section with the at least one inflatable channel or cuff in anexpanded state; c) positioning the graft section in the main cavityportion of the mold with the at least one inflatable channel or cuff ofthe graft section in an unexpanded state and positioned to expand intocorresponding channel or cuff cavity portions of the main cavityportion; d) injecting pressurized fluid into the at least one inflatablechannel or cuff to expand the at least one inflatable channel or cuff;e) fixing the graft material of the at least one inflatable channel orcuff with the at least one inflatable channel or cuff in an expandedstate.
 57. The method of claim 56 further comprising positioning apressure line comprising an elongate conduit having a permeable sectionwith a permeability gradient in fluid communication with at least oneinflatable channel or cuff of the graft section and injecting thepressurized fluid into the at least one inflatable channel or cuffthrough the permeable section of the pressure line.
 58. The method ofclaim 57 wherein the pressure line is positioned within a temporarylongitudinal inflation channel of the graft section which is in fluidcommunication with at least one inflatable channel of the graft section,said temporarily longitudinal inflation channel being sealed inlocations between adjacent portions of the at least one inflatablechannel after the at least one inflatable channel has been expanded byinjection of pressurized fluid and after the graft material of the atleast one inflatable channel has been fixed.
 59. The method of claim 56further comprising disposing an internal radial support within the graftsection prior to expansion of the at least one inflatable channel orcuff.
 60. The method of claim 59 wherein the internal radial supportcomprises a mandrel which is disposed within the graft section prior toplacing the graft section into the mold so as to radially support theinside surface of the graft section during injection of the pressurizedfluid.
 61. The method of claim 56 wherein the graft material of the atleast one inflatable channel or cuff is fixed by sintering.
 62. Themethod of claim 56 wherein the graft material of the entire graftsection is fixed.
 63. The method of claim 56 wherein the graft materialis fixed by heating to a temperature of about 335 to about 380 degreesCelsius.
 64. The method of claim 56 wherein the graft material comprisesePTFE.
 65. The method of claim 56 wherein the pressurized fluid is a gaswhich is injected into the input end of the pressure line at a rate ofabout 2 to about 30 scfh.
 66. The method of claim 56 wherein thepressurized fluid is a gas which is injected into the input end of thepressure line at a rate of about 5 to about 6 scfh.
 67. The method ofclaim 56 wherein the pressurized fluid is a gas which is injected at arate of about 2 to about 15 scfh.
 68. The method of claim 56 wherein thepressurized fluid is a gas which is injected into the pressure line at apressure of about 5 to about 30 psi.
 69. The method of claim 56 whereinthe pressurized fluid is a gas which is injected into the pressure lineat a pressure of about 35 to about 65 psi.
 70. A method of forming atleast one inflatable channel or cuff of an endovascular graft or sectionthereof comprising: a) providing a graft section with at least oneinflatable channel or cuff formed between layers of graft material ofthe graft section in an unexpanded state; b) providing a mold comprisinga main cavity portion having an inside surface contour that correspondsto an outside surface contour of the graft section with the at least oneinflatable channel or cuff in an expanded state; c) positioning thegraft section in the main cavity portion of the mold with the at leastone inflatable channel or cuff of the graft section in an unexpandedstate positioned to expand into corresponding channel or cuff cavityportions of the main cavity portion; d) injecting pressurized liquidinto the at least one inflatable channel or cuff to expand the at leastone inflatable channel or cuff; and e) fixing the graft material of theat least one inflatable channel or cuff with the at least one inflatablechannel or cuff in an expanded state.
 71. The method of claim 70 whereinsome expansion of the inflatable channel or cuff is carried out by vaporpressure from boiling of pressurized liquid during fixing of the graftmaterial.
 72. An outer constraint means for manufacture of anendovascular graft or section thereof which has at least one inflatablechannel or cuff, comprising: one or more of outer constraint body meansconfigured to produce an outer constraint means having a main cavitymeans configured to radially constrain an outside surface contour of agraft section with the at least one inflatable channel or cuff in anexpanded state.
 73. An outer constraint means for manufacture of anendovascular graft or section thereof which has at least one inflatablechannel or cuff, comprising: a first outer constraint body means havinga main cavity means configured to correspond to an outside surfacecontour of a graft section with the at least one inflatable channel orcuff in an expanded state; and a second outer constraint body meansconfigured to mate with the first outer constraint body means andconfigured to correspond to an outside surface contour of the graftsection with the at least one inflatable channel or cuff in an expandedstate.
 74. A pressure line for use in the manufacture of an endovasculargraft or section thereof comprising: an elongate gas containment meanshaving an input end, an output end and means for producing apermeability gradient which increases with distance from the input endalong a section of the elongate gas containment means.
 75. An assemblyfor manufacture of an endovascular graft or section thereof which has atleast one inflatable cuff or channel on a graft section, comprising: a)an interior surface support means configured to support an insidesurface of the graft section; b) the graft section having at least oneinflatable cuff or channel disposed about at least a portion of theinterior surface support means; c) a pressure line comprising anelongate gas containment means having an input end, an output end andmeans for producing a permeability gradient which increases withdistance from the input end along a section of the elongate gascontainment means; d) an outer constraint means at least partiallydisposed about the graft section, the pressure line and the interiorsurface support means, comprising a plurality of outer constraint bodymeans configured to mate with at least one of the other outer constraintbody means to produce an assembled outer constraint means configured toradially constrain an outside surface contour of the graft section withthe at least one inflatable channel or cuff in an expanded state duringexpansion of the cuff or channel.
 76. A method of forming at least oneinflatable channel or cuff of an endovascular graft or section thereofcomprising the steps of: a) providing an endovascular graft section withat least one inflatable channel or cuff formed between layers of graftmaterial of the graft section in an unexpanded state; b) providing anouter constraint means configured to radially constrain an outsidesurface contour of the graft section with the at least one inflatablechannel or cuff in an expanded state during expansion of the cuff orchannel; c) positioning the graft section within the outer constraintmeans with the at least one inflatable channel or cuff of the graftsection in an unexpanded state positioned to expand into a correspondingchannel or cuff cavity of the outer constraint means; d) expanding theat least one inflatable channel or cuff with pressurized fluid; e)fixing the graft material of the at least one inflatable channel or cuffwith the at least one inflatable channel or cuff in an expanded state.77. The method of claim 76 further comprising the step of positioning apressure line comprising an elongate gas containment means having aninput end, an output end and means for producing a permeability gradientwhich increases with distance from the input end along a section of theelongate gas containment means and passing expansion material into theat least one inflatable channel or cuff through the means for producinga permeability gradient.
 78. The method of claim 76 further comprisingdisposing an interior surface support means configured to support aninside surface of the graft section within the graft section prior toexpansion of the at least one inflatable channel or cuff.